Pumping Test to Determine Permeability Ratio

Field pumping tests on fully and partially penetrating wells in the alluvial valley of the lower Arkansas River indicate a ratio of horizontal to vertical permeability of approximately 2. The results of these test are considered typical for alluvial sands of the Arkansas River where the aquifer is fairly homogeneous and there are no impervious layers of significant areal extent. The ratio k_H/k_V was determined by comparing hydrostatic potentials around the test well with theoretical potentials determined from electrical analogy model studies, and from Muskat's equation for flow to partially penetrating wells using well flows and drawdowns measured in the field. The average horizontal coefficient of permeability (k_H) was found, from the test results, to be approximately 700×10^-4 cm per sec. Tests on a fully penetrating well, using a well flow meter to measure the flow from various strata, indicated variations in the horizontal permeability of the various strata from 200 to 1,200×10^-4 cm per sec. The pumping tests also indicated a logarithmic relationship between the effective grain size (D₁₀) and the coefficient of horizontal permeability (k_H).